Want new dahlias for free? Discover how easy it is to force tubers in late winter and take dahlia cuttings

With vibrant blooms in different colors, sizes, and forms to choose between, there is so much to love about growing dahlias. But the cost of buying dahlia tubers can add up, which is why forcing existing tubers and taking dahlia cuttings offers an easy and inexpensive way to add to your collection.

Forcing the tubers is a trick which encourages dahlias to grow outside of their natural season. When you lift and overwinter dahlias indoors to protect the tubers from seasonal colds and frosts, they can’t go back outside until late spring once the temperatures rise.

However, if you plant dahlias indoors in February or March you encourage the plant to grow earlier. The reward for that is an extended season of dahlia blooms, plus you can take plant cuttings and get more of your favorite dahlias for free. These cuttings quickly grow and can start flowering by the end of the first season. If you grow dahlias and want to propagate more of your favorites, this guide shows how simple it is to take dahlia cuttings.

A guide to forcing tubers and taking dahlia cuttings

Forcing dahlias indoors is quick and easy and a task that can be started in February. It is a seasonal gardening task that can be done with all types of dahlias. Whether you adore single, cactus, or pompon dahlias, forcing dahlia tubers in late winter means longer blooming seasons and the opportunity to take dahlia cuttings.

Forcing dahlia tubers - why and how

Forcing dahlias and taking cuttings was an annual late winter task during my time as a professional gardener, when getting long flowering seasons and building a dahlia collection on a budget was important.

We did large dahlia displays in one historic public garden and visitors adored the blooms - so keeping dahlias blooming for as long as possible was important. Plus taking dahlia cuttings allowed us to maintain a large stock of plants - and propagate more of the most popular dahlia varieties.

Forcing dahlia tubers is done in February or March by potting them up into containers filled with a quality potting mix and keeping them someplace warm. I always put them in a heated greenhouse, but the pots can go on a heat mat or a warm windowsill. Give the tubers heat, light, and regular water and shoots will develop quickly.

How to take dahlia cuttings in 7 steps

It should take around three weeks until the new dahlia shoots are 2-3 inches long and ready to be used for cuttings. Dahlia cuttings can be taken and rooted successfully in the following 7 simple steps:

1. Fill small pots with a potting mix suitable for starting seeds or cuttings and make a hole in the center of the compost
2. Use a clean, sharp knife to cut the shoot, taking a small sliver of the tuber at the same time
3. Remove the lower leaves from the cutting and dip the end of the cutting in rooting hormone
4. Place the cutting into the pre-made hole and press the soil around it to remove air pockets
5. Put the container into a propagator or put a clear plastic bag over the pot to maintain humidity. The cuttings will work best when the soil and air temperature is kept at 65-75°F
6. Keep the compost moist, but not waterlogged. It takes 2-4 weeks for roots to develop, closely followed by new leaves
7. Transplant the new dahlia outside, after a period of hardening off, once the frosts have ended and temperatures have risen

FAQs

Will dahlia cuttings root in water?

Dahlia cuttings can root when part-submerged in a container of water and placed on a bright windowsill where it can get lots of indirect sunlight. The water does need to be changed every few days and roots should develop within 2-4 weeks. However, the preferable way to root dahlia cuttings is to do so in a container filled with potting mix to guarantee the development of strong, healthy roots.

Another inexpensive way to add to your collection is to harvest dahlia seeds and grow them into new plants. Growing dahlias from seed is simple and you can sow seeds indoors around 6-8 weeks before your last frost for healthy seedlings to go outside in spring.

The drawback to collecting and sowing dahlia seeds is that there is no guarantee that the seeds you plant will grow into the same parent plant. Taking cuttings or dividing dahlia tubers are the routes to go if you want a clone of a particular dahlia.